Is fluency in a foreign language considered to be a good extracurricular for my college apps?

I'd say yes, but I wouldn't really say it's an extracurricular unless you are actively doing something to maintain/learn the languages. If you were just raised to speak two other languages by your parents, that could be a good diversity essay, but isn't really an extracurricular. However, if you learned them by yourself, or for example were putting in extra time outside of class towards a language you were learning in school, then it would be an extracurricular. I'd put it on your application either way though.

Definitely that will be something outstanding for you as not everyone speak that many languages, so can earn a certification but it isn’t necessary since if you speak it, then you’ll say the true, however it is up to you if you want to earn one.

Absolutely! Being fluent in languages other than English is a huge standout from the crowd, since not many seniors even continue taking a foreign language by their senior year. You should definitely talk more about this in your essays, and how learning these languages has impacted your perspective of your surroundings. Here is a link for getting bilingual certification if you would like to get certified for speaking two other languages: https://theglobalseal.com/bilingual-certification